selecting random numbers

i have a matrix 10x10 i want to select random matrix of 5x5 but the selected matrix must be in same order as the original matrix,if i choose 20x20 the random matrix must be 10x10

please help

[Wayne King]

Can you elaborate on what you mean by "...must be in the same order" In your example all you're telling us is that the row and column dimensions must be 1/2 the original matrix.

[kash]

yes wayne the row and column dimensions must be 1/2 the original matrix.

must be in same order the the original matrix in is ascending order ,so i want the same order

Answer 1

[Image Analyst]

Just use rand() to randomly pick a row and column in the range 1 to half the width and extract it subMatrix = fullMatrix(row1:row2, col1:col2); I'm sure you can figure out how to get row1, etc. using rand. (I'm leaving some of the work to you in case this is a homework problem, which it sounds like it is.)